1. Field of the Invention
The present invention generally relates to centralized shared storage systems for collaborative non-linear editing and manipulation of digital video and audio files.
2. Description of the Prior Art
Non-linear video and audio editing systems (NLE's) that can perform random access on the source material are typically set up on independent computer workstations having a means to input digital or analog audio and video as well as software for editing the inputted audio and video.
In such systems, video and sound (e.g., for film and television production) are digitized, or otherwise digital video is imported into the computer for storage on a hard disk or other storage media. Subsequently, the digital media can be manipulated with software such as, Avid's Xpress® Pro, Media Composer Adrenaline, or Liquid, Apple's Final Cut Pro, Boris's Media 100, Sony Vegas, Thompson-Grass Valley's Edius, and Adobe's Premiere Pro. Various editing tasks can then be performed on the imported video before it is saved, exported to another medium, or encoded for transfer to other storage media, e.g., a CD or DVD.
While a given television or film production facility may have multiple NLE workstations, the digital media files that are stored and accessed by each NLE—video files, audio files, graphics, stills, etc. —typically reside locally on that workstations' internal hard drives or on external hard drives that are directly attached to the workstation.
Several manufacturers offer products that allow multiple NLEs (often from the manufacturer's own product line) to be attached to a centralized storage network. Attaching NLEs to a common centralized storage network that every user and workstation can access vastly improves the efficiency of editing with NLEs and also allows a workflow that fosters collaboration and creativity. By storing media files in a centralized location, many editors can work simultaneously on the same project without having to duplicate the media files on each system. For example, in a news operation, a reporter can edit a story while an editor creates “coming up next promos” from the same material. In another example from the world of documentaries and feature films, new media files can be added to the system—captured—at one set of workstations while editors edit those files at another set of workstations. Similarly, one editor can tweak the sound for finished parts of the story while another editor works on parts of the story that still need to be edited. Thus, supervisors can review the work of subordinates while the subordinates continue working on a project. Furthermore, editors can use any workstation that's available—because the media files don't have to be directly attached to the workstation that happens to be available.
With all the advantages of attaching NLEs to a common centralized storage network, it would seem that every facility with two or more NLE systems would use centralized storage. However, the high cost of the currently available systems is a significant barrier for many owners of NLE systems. Furthermore, many commercial products that are marketed to provide centralized storage for collaborative editing and manipulation of video and audio files do not provide some key capabilities that users need.
Setting tip a comprehensive and effective “home grown,” centralized storage system is not a practical alternative in many cases, because shared media files must be stored in such a way that the files are managed and kept safe from accidental erasure and so that the NLE workstations accessing those files do not come into conflict with one another.
For instance, Avid® Technology's products such as Xpress Pro and Media Composer Adrenaline (both Windows and Macintosh versions) scan all the media files they can see on the various storage devices that are accessible to the workstation and then create a database of the clips—writing the database files to the very same folders where the media files are found. If multiple workstations try to access the same media files folder over a network, each workstation will try to rewrite the database files—sometimes causing workstations to crash or corrupt each other's projects.
Another problem arises when capturing new media files onto a system using Xpress DV Xpress Pro, Adrenaline, etc. As new material is being captured from videotape, the digital audio and video media files are temporarily stored in a subfolder called “Creating” and are given temporary names until the capture process is finished. If two or more workstations were capturing at the same time, each workstation would be storing temporary files in the same “Creating” subfolder and trying to give those files the same name—thus, causing a conflict.
Avid® Technology products are not the only NLEs that present such centralized storage difficulties. When working on other industry leading NLEs such as Apple's Final Cut Pro and Adobe Premiere Pro, if multiple users attempt to read and write the same media files on a simple networked volume there is a serious danger that media files can be accidentally—or even maliciously—erased to the detriment of some or all members of the group.
Recent changes in the capabilities of stand-alone NLE applications such as provided by Avid® Technology pertain to the use of the MXF (Multimedia Exchange Format) files. In older versions of these applications, Avid only supported its own OMF file format, all media files in a given volume (i.e., files with the extensions *.omf *.aif, and *.wav) had to be stored in a single directory one level down from the root level of a volume. For example, for a given storage volume “X”, whether a local volume or a volume mounted over a network connection, Avid would require that all media files were stored as such:
X = Storage Volume (root level)  /OMFI MediaFiles (directory where files had to be store)    MediaFiles.omf    MediaFiles.aif    MediaFiles.wav    MediaDatabaseFiles
With the introduction of support for MXF files, Avid Technology opened the door to some new strategies to support collaboration by establishing a new directory hierarchy in which files can be stored. Most importantly, Avid's NLE application allows for multiple folders to be created at the level where media files must be located. The new directory hierarchy generally looks as follows:
X = Storage Volume (root level)  /Avid MediaFiles (directory one level down from root level)    /MXF (subdirectory two levels down)      /1 (subdirectory three levels down)        VideoFiles.mxf        AudioFiles.mxf        MediaDatabaseFiles      /2 (subdirectory three levels down)        VideoFiles.mxf        AudioFiles.mxf        MediaDatabaseFilesand so on.
A standalone Avid NLE application working with MXF format files will have at least one subdirectory below the “MXF” directory, starting with the number “1”. When the “1” directory gets to a certain number of files, Avid will create a “2” directory. And when the “2” directory gets full, Avid will create a “3” directory; and the process repeats. It is also possible for users to create directories with much higher numbers (for example, “456”, “39876”) and Avid will use those directories in a similar same way. It is also possible to put media files into subdirectories that have names (i.e., “john”, “peter”, “susan”). While the media files contained within directories with names that contain non-digit characters will be seen by the Avid NLE applications, Avid will not create or modify media database files within such directories.
It would be highly desirable to exploit these various NLE application characteristics, to provide a substantially improved and novel way of facilitating multiple NLE workstations to work with a common pool of media files.